diff --git a/src/config/config.ml b/src/config/config.ml
index 8192ffb9..ce0dd485 100644
--- a/src/config/config.ml
+++ b/src/config/config.ml
@@ -106,9 +106,22 @@ let normalize_path path =
   | "" -> Filename.current_dir_name
   | normalized_path -> normalized_path
 
+let rec add_filepaths acc path =
+  match Utils.Filepath.kind ~exclude:(fun _ -> false) path with
+  | Cmi | Cmt -> Utils.StringSet.add path acc
+  | Dir ->
+      Sys.readdir path
+      |> Array.fold_left
+        (fun acc sub_path ->
+          let path = Filename.concat path sub_path in
+          add_filepaths acc path
+        )
+        acc
+  | Ignore -> acc
+
 let exclude path config =
   let path = normalize_path path in
-  let excluded_paths = Utils.StringSet.add path config.excluded_paths in
+  let excluded_paths = add_filepaths config.excluded_paths path in
   {config with excluded_paths}
 
 let is_excluded path config =
@@ -116,11 +129,11 @@ let is_excluded path config =
   Utils.StringSet.mem path config.excluded_paths
 
 let add_reference_path path config =
-  let references_paths = Utils.StringSet.add path config.references_paths in
+  let references_paths = add_filepaths config.references_paths path in
   {config with references_paths}
 
 let add_path_to_analyze path config =
-  let paths_to_analyze = Utils.StringSet.add path config.paths_to_analyze in
+  let paths_to_analyze = add_filepaths config.paths_to_analyze path in
   {config with paths_to_analyze}
 
 (* Command line parsing *)
diff --git a/src/config/config.mli b/src/config/config.mli
index cca086bd..5daa27cd 100644
--- a/src/config/config.mli
+++ b/src/config/config.mli
@@ -22,10 +22,12 @@ type t = private
   ; internal : bool (** Keep track of internal uses for exported values *)
   ; underscore : bool (** Keep track of elements with names starting with [_] *)
   ; paths_to_analyze : Utils.StringSet.t
-      (** Paths found in the command line and considered for analysis *)
-  ; excluded_paths : Utils.StringSet.t (** Paths to exclude from the analysis *)
+      (** Cmi and cmt filepaths found by exploring the paths provided in the
+          command line and considered for analysis *)
+  ; excluded_paths : Utils.StringSet.t
+      (** Cmi and cmt filepaths to exclude from the analysis *)
   ; references_paths : Utils.StringSet.t
-      (** Paths to explore for references only *)
+      (** Cmi and cmt filepaths to explore for references only *)
   ; sections : Sections.t (** Config for the different report sections *)
   }
 
diff --git a/src/deadCode.ml b/src/deadCode.ml
index 8e3393e1..76b26c85 100644
--- a/src/deadCode.ml
+++ b/src/deadCode.ml
@@ -342,24 +342,12 @@ let collect_references =                          (* Tast_mapper *)
                 type_declaration
               }
 
-(* Checks the nature of the file *)
-let kind fn =
-  let state = State.get_current () in
-  if not (Sys.file_exists fn) then begin
-    prerr_endline ("Warning: '" ^ fn ^ "' not found");
-    `Ignore
-  end else if Config.is_excluded fn state.config then `Ignore
-  else if Sys.is_directory fn then `Dir
-  else if Filename.check_suffix fn ".cmi" then `Cmi
-  else if Filename.check_suffix fn ".cmt" then `Cmt
-  else `Ignore
-
 
 let regabs state =
   let fn = State.File_infos.get_sourcepath state.State.file_infos in
-  hashtbl_add_unique_to_list abspath (Utils.unit fn) fn;
+  hashtbl_add_unique_to_list abspath (Utils.Filepath.unit fn) fn;
   if !DeadCommon.declarations then
-    hashtbl_add_unique_to_list main_files (Utils.unit fn) ()
+    hashtbl_add_unique_to_list main_files (Utils.Filepath.unit fn) ()
 
 
 let read_interface fn cmi_infos state = let open Cmi_format in
@@ -370,7 +358,7 @@ let read_interface fn cmi_infos state = let open Cmi_format in
         if State.File_infos.has_sourcepath state.file_infos then
           State.File_infos.get_sourceunit state.file_infos
         else
-        Utils.unit fn
+        Utils.Filepath.unit fn
       in
       let module_id =
         State.File_infos.get_modname state.file_infos
@@ -395,11 +383,11 @@ let assoc decs (loc1, loc2) =
   let is_implem fn = fn.[String.length fn - 1] <> 'i' in
   let has_iface fn =
     fn.[String.length fn - 1] = 'i'
-    || ( Utils.unit fn = sourceunit
+    || ( Utils.Filepath.unit fn = sourceunit
       && DeadCommon.file_exists (fn ^ "i"))
   in
   let is_iface fn loc =
-    Hashtbl.mem decs loc || Utils.unit fn <> sourceunit
+    Hashtbl.mem decs loc || Utils.Filepath.unit fn <> sourceunit
     || not (is_implem fn && has_iface fn)
   in
   if fn1 <> _none && fn2 <> _none && loc1 <> loc2 then begin
@@ -420,7 +408,7 @@ let clean references loc =
   let state = State.get_current () in
   let sourceunit = State.File_infos.get_sourceunit state.file_infos in
   let fn = loc.Lexing.pos_fname in
-  if (fn.[String.length fn - 1] <> 'i' && Utils.unit fn = sourceunit) then
+  if (fn.[String.length fn - 1] <> 'i' && Utils.Filepath.unit fn = sourceunit) then
     LocHash.remove references loc
 
 let eof loc_dep =
@@ -446,7 +434,7 @@ let eof loc_dep =
 
 
 (* Starting point *)
-let rec load_file fn state =
+let load_file fn state =
   let init_and_continue state fn f =
     match State.change_file state fn with
     | Error msg ->
@@ -458,8 +446,9 @@ let rec load_file fn state =
         (* TODO: stateful computations should take and return the state when possible *)
         state
   in
-  match kind fn with
-  | `Cmi when !DeadCommon.declarations ->
+  let exclude filepath = Config.is_excluded filepath state.State.config in
+  match Utils.Filepath.kind ~exclude fn with
+  | Cmi when !DeadCommon.declarations ->
       last_loc := Lexing.dummy_pos;
       if state.State.config.verbose then Printf.eprintf "Scanning %s\n%!" fn;
       init_and_continue state fn (fun state ->
@@ -468,7 +457,7 @@ let rec load_file fn state =
       | Some cmi_infos -> read_interface fn cmi_infos state
       )
 
-  | `Cmt ->
+  | Cmt ->
       let open Cmt_format in
       last_loc := Lexing.dummy_pos;
       if state.config.verbose then Printf.eprintf "Scanning %s\n%!" fn;
@@ -501,14 +490,10 @@ let rec load_file fn state =
       | _ -> () (* todo: support partial_implementation? *)
       )
 
-  | `Dir ->
-      let next = Sys.readdir fn in
-      Array.sort compare next;
-      Array.fold_left
-        (fun state s -> load_file (fn ^ "/" ^ s) state)
-        state
-        next
-      (* else Printf.eprintf "skipping directory %s\n" fn *)
+  | Dir ->
+      (* TODO : better error handling *)
+      failwith ("Internal error : Unexpected directory "
+                ^ fn ^ ". Only .cmi and .cmt are expected")
 
   | _ -> state
 
@@ -518,7 +503,7 @@ let rec load_file fn state =
 (* Prepare the list of opt_args for report *)
 let analyze_opt_args () =
   DeadArg.eocb ();
-  let dec_loc loc = Hashtbl.mem main_files (Utils.unit loc.Lexing.pos_fname) in
+  let dec_loc loc = Hashtbl.mem main_files (Utils.Filepath.unit loc.Lexing.pos_fname) in
   let all = ref [] in
   let opt_args_tbl = Hashtbl.create 256 in
 
diff --git a/src/deadCommon.ml b/src/deadCommon.ml
index bd9344ad..7db05bac 100644
--- a/src/deadCommon.ml
+++ b/src/deadCommon.ml
@@ -127,7 +127,7 @@ let find_path fn l =
   List.find (is_sub_path ~sep fn) l
 
 let find_abspath fn =
-  find_path fn (hashtbl_find_list abspath (Utils.unit fn))
+  find_path fn (hashtbl_find_list abspath (Utils.Filepath.unit fn))
 
 let file_exists fn =
   match find_abspath fn with
@@ -152,7 +152,7 @@ let exported ?(is_type = false) (flag : Config.Sections.main_section) loc =
   && (is_type
     || state.config.internal
     || fn.[String.length fn - 1] = 'i'
-    || sourceunit <> Utils.unit fn
+    || sourceunit <> Utils.Filepath.unit fn
     || not (file_exists (fn ^ "i")))
 
 
@@ -362,7 +362,7 @@ module VdNode = struct
         if not (LocSet.is_empty worklist) then
           let loc = LocSet.choose worklist in
           let wl = LocSet.remove loc worklist in
-          if Utils.unit loc.Lexing.pos_fname <> sourceunit then
+          if Utils.Filepath.unit loc.Lexing.pos_fname <> sourceunit then
             List.iter (LocHash.remove parents) loc_list
           else begin
             LocHash.replace met loc ();
@@ -394,7 +394,7 @@ let export ?(sep = ".") path u stock id loc =
     will create value definitions whose location is in set.mli
   *)
   if not loc.Location.loc_ghost
-  && (u = Utils.unit loc.Location.loc_start.Lexing.pos_fname || u == _include)
+  && (u = Utils.Filepath.unit loc.Location.loc_start.Lexing.pos_fname || u == _include)
   && check_underscore (Ident.name id) then
     let state = State.get_current () in
     let builddir = State.File_infos.get_builddir state.file_infos in
diff --git a/src/state/file_infos.ml b/src/state/file_infos.ml
index ec7d5007..4a3eace1 100644
--- a/src/state/file_infos.ml
+++ b/src/state/file_infos.ml
@@ -23,7 +23,7 @@ let empty = {
 let init_from_cmt_infos cmt_infos cmt_file =
   let builddir = cmt_infos.Cmt_format.cmt_builddir in
   let sourcepath =
-    Option.map Utils.remove_pp cmt_infos.cmt_sourcefile
+    Option.map Utils.Filepath.remove_pp cmt_infos.cmt_sourcefile
     |> Option.map (Filename.concat builddir)
   in
   let modname = cmt_infos.cmt_modname in
@@ -50,13 +50,8 @@ let init_from_cmt cmt_file =
 
 
 let sourcefname_of_cmi_infos cmi_unit cmi_infos =
-  (* Use lowercased units because dune wrapped lib's module units follow the
-     pattern : `<lib>__<Captilized_module>` while the original module unit may
-     not be capitalized.
-  *)
-  let cmi_unit = String.lowercase_ascii cmi_unit in
   let candidate_of_fname fname =
-    let src_unit = Utils.unit fname |> String.lowercase_ascii in
+    let src_unit = Utils.Filepath.unit fname in
     if String.equal src_unit cmi_unit then
       `Identical fname
     else if String.ends_with ~suffix:src_unit cmi_unit then
@@ -112,7 +107,7 @@ let init_from_cmi_infos ?with_cmt cmi_infos cmi_file =
   let sourcepath =
     let sourcepath =
       (* Try to find a sourcepath in the cmi_infos *)
-      let cmi_unit = Utils.unit cmi_file in
+      let cmi_unit = Utils.Filepath.unit cmi_file in
       let sourcefname = sourcefname_of_cmi_infos cmi_unit cmi_infos in
       match sourcefname, builddir with
       | Some fname, Some builddir -> Some (Filename.concat builddir fname)
@@ -199,7 +194,8 @@ let get_builddir t =
 
 let get_sourcepath t =
   match t.sourcepath with
-  | Some sourcepath -> sourcepath
+  | Some sourcepath ->
+      sourcepath
   | None -> match t.builddir with
     | Some builddir ->
       Printf.sprintf "!!UNKNOWN_SOURCEPATH_IN<%s>_FOR_<%s>!!"
@@ -209,7 +205,7 @@ let get_sourcepath t =
 
 let get_sourceunit t =
   match t.sourcepath with
-  | Some sourcepath -> Utils.unit sourcepath
+  | Some sourcepath -> Utils.Filepath.unit sourcepath
   | None -> "!!UNKNOWN_SOURCEUNIT_FOR<" ^ t.cmti_file ^ ">!!"
 
 let get_modname t = t.modname
diff --git a/src/utils.ml b/src/utils.ml
index cf66a239..bb524456 100644
--- a/src/utils.ml
+++ b/src/utils.ml
@@ -1,11 +1,34 @@
-let remove_pp fn =
-  let ext = Filename.extension fn in
-  let no_ext = Filename.remove_extension fn in
-  match Filename.extension no_ext with
-  | ".pp" -> Filename.remove_extension no_ext ^ ext
-  | _ -> fn
-
-let unit fn =
-  Filename.remove_extension (Filename.basename fn)
+module Filepath = struct
+
+  type t = string
+
+  let remove_pp filepath =
+    let ext = Filename.extension filepath in
+    let no_ext = Filename.remove_extension filepath in
+    match Filename.extension no_ext with
+    | ".pp" -> Filename.remove_extension no_ext ^ ext
+    | _ -> filepath
+
+  let unit filepath =
+    Unit_info.modname_from_source filepath
+
+  type kind =
+    | Cmi
+    | Cmt
+    | Dir
+    | Ignore
+
+  (* Checks the nature of the file *)
+  let kind ~exclude filepath =
+    if exclude filepath then Ignore
+    else if not (Sys.file_exists filepath) then (
+      prerr_endline ("Warning: '" ^ filepath ^ "' not found");
+      Ignore
+    )
+    else if Sys.is_directory filepath then Dir
+    else if Filename.check_suffix filepath ".cmi" then Cmi
+    else if Filename.check_suffix filepath ".cmt" then Cmt
+    else Ignore
+end
 
 module StringSet = Set.Make(String)
diff --git a/src/utils.mli b/src/utils.mli
index ce4b30e9..f9fe1424 100644
--- a/src/utils.mli
+++ b/src/utils.mli
@@ -1,5 +1,25 @@
-val remove_pp : string -> string
+module Filepath : sig
 
-val unit : string -> string
+  type t = string
+
+  val remove_pp : t -> t
+  (** [remove_pp filepath] removes the `.pp` extension (if it exists) from
+      [filepath]. Eg. [remove_pp "dir/foo.pp.ml" = "dir/foo.ml"] *)
+
+  val unit : t -> string
+  (** [unit filepath] estimates the compilation unit of [filepath] *)
+
+  type kind =
+    | Cmi (** .cmi file *)
+    | Cmt (** .cmt file *)
+    | Dir (** Directory *)
+    | Ignore (** Irrelevant for the analyzer *)
+
+  val kind : exclude:(t -> bool) -> t -> kind
+  (** [kind ~exclude filepath] returns the kind of [filepath].
+      If [exclude filepath = true], [filepath] does not exists, or [filepath]
+      does not fit in another kind, then its kind is [Ignore].
+      Other kinds are self explanatory. *)
+end
 
 module StringSet : Set.S with type elt = String.t